Field of the Disclosure
The present disclosure relates to a thin film transistor (TFT) substrate, and particularly, to a TFT substrate including a TFT formed on a plastic substrate, a display panel including the same, and a method of manufacturing the same.
Discussion of the Related Art
As the times advance in an information-oriented society, flat panel display (FPD) devices which have good characteristics such as thin, light weight, and low power consumption are increasing in importance. Examples of FPD devices include liquid crystal display (LCD) devices, plasma display panels (PDPs), organic light-emitting display devices, etc. Recently, electrophoretic display (EPD) devices are being widely used as one type of FPD device.
A display panel used in a display device is manufactured with a glass carrier, a quartz substrate, or the like. However, the above-described substrates are easily cracked and are heavy. Therefore, the glass carrier and the quartz substrate are not suitable for manufacturing a flexible display device. Therefore, a method of forming a TFT on a substrate (for example, flexible plastic) having flexibility is being applied for manufacturing a flexible display device.
A TFT is being widely used as a switching element in a display panel such as a liquid crystal panel or an organic light-emitting display panel. Therefore, a TFT substrate where a TFT is formed is a fundamental element of a display panel configured for a display device.
To provide an additional description, recently research for flexible display panels is being actively pursued. The flexible display panel needs to be able to be bent or curved. Therefore, instead of glass, a polymer material (i.e., plastic) such as polyimide (PI) is being used as a material of a TFT substrate.
FIG. 1 is a circuit diagram for describing a pixel structure of a related art organic light-emitting display panel.
A pixel P of the related art organic light-emitting display panel, as illustrated in FIG. 1, includes an organic light-emitting diode (OLED), a switching transistor Tsw, a driving transistor Tdr, and a capacitor Cst. In FIG. 1, the switching transistor Tsw and the driving transistor Tdr are implemented in an N-type, but are not limited thereto. For example, the switching transistor Tsw and the driving transistor Tdr may be implemented in a P-type.
Each of the switching transistor and the driving transistor is configured with a TFT.
FIG. 2 is a cross-sectional view of one pixel of a related art flexible organic light-emitting display panel.
In the related art flexible organic light-emitting display panel, as illustrated in FIG. 2, a lower substrate 10 formed of plastic is attached to an auxiliary substrate A. An organic light-emitting diode (OLED) connected to a driving transistor Tdr is formed on the lower substrate 10. The auxiliary substrate A includes a glass carrier 80 and a sacrificial layer 85. The auxiliary substrate A is detached from the lower substrate 10, where the OLED is formed, through a laser release process.